Conventionally, there has been a water purifier which purifies raw water such as tap water and well water and supplies purified water. In a general water purifier such as a household faucet-direct-coupled water purifier, after supplying purified water, water remains stagnant in a filtering medium (water purification cartridge) and a water passage inside the water purifier. When the water is left stagnant inside the water purifier for a long time, bacteria propagate inside the water purifier, thereby causing insanitation.
In particular, in a water purifier in which a part of a filtering medium or the whole of the filtering medium is composed of activated carbon, bacteria easily propagate in stagnant water inside a water passage on a secondary side on which the water has passed through the filtering medium, that is, a side downstream of the filtering medium. This is because a chloride component in raw water is removed by the activated carbon in the filtering medium.
Therefore, as a point of caution for use of the water purifier, a water purifier manufacturer encourages a user to perform the so-called water discarding that is a process in which purified water to be first used after resuming the use of the water purifier, such as purified water first supplied from the water purifier every day and purified water first supplied from the water purifier when the water purifier has not been used for some days and the use of the water purifier is resumed, is discharged for a predetermined period of time and discarded.
However, whether the water discarding is performed in reality when the use of the purified water is started after resuming the use of the water purifier, how long the water discarding is performed, and what quantity of water is discarded are left to the judgment of a user of the water purifier. Therefore, in a case where the user forgets to perform the water discarding and the water discarding is not sufficiently performed, a health hazard may be posed to the user.
Therefore, in order to allow a user to perform appropriately perform the water discarding, a water purifier having a function of notifying a user of a period of time required to perform the water discarding and a water purifier which automatically performs the water discarding have been proposed.
For example, Japanese Patent Application Laid-Open Publication No. 9-141250 (Patent Literature 1) discloses a water purification apparatus which issues an alarm to perform the water discarding and cleaning for a period of time enough to discard water which has remained stagnant inside the water purification apparatus when a state in which water is not passing continues for a predetermined period of time or more. It is described that in this water purification apparatus, cleaning time may be changed in accordance with a length of time during which the water is not passing. In addition, it is described that based on a detection signal detected by a flow sensor during the execution of the water discarding, water discarding time may be adjusted.
In a water purifier disclosed by Japanese Patent Application Laid-Open Publication No. 11-169844 (Patent Literature 2), when the water purifier is not used for a given period of time, an orange-colored LED is being lit up until discharging the water remaining inside the water purifier is finished, and thereafter, a green LED is lit up, thereby notifying a user of whether or not the purified water can be used.
In addition, in water purification apparatuses disclosed by Japanese Patent Application Laid-Open Publication No. 2006-15232 (Patent Literature 3) and Japanese Patent Application Laid-Open Publication No. 2006-142244 (Patent Literature 4), a shutting-off condition of a water shutoff valve is detected and a period of time is calculated and displayed as the number of days during which water has remained stagnant. When the number of days during which the water has remained stagnant comes to be greater than or equal to a predetermined water-remaining period of time and a user discards the remaining water from a water pipe, information on a backward counter, which is used as an indication of a quantity of the discarded water, is displayed and concurrently, a indication light is displayed so as to blink on and off.
In a water purification apparatus disclosed by Japanese Patent Application Laid-Open Publication No. 2002-263638 (Patent Literature 5), when a time interval from when a water tap for flowing tap water into an activated carbon tank is opened up to when the water tap is next opened, which is greater than or equal to a given period of time, has passed, sterilization and cleaning are performed by flowing the tap water from a secondary side of the activated carbon tank to the water tap for a predetermined set period of time.
In a water purification system disclosed by Japanese Patent Application Laid-Open Publication No. 2007-217916 (Patent Literature 6), when a period of time during which purified tap water has remained stagnant exceeds a predetermined set period of time, a water discarding solenoid valve is opened and a process to discard the remaining water is performed. When a predetermined period of time during which the water discarding solenoid valve remains open has passed, the water discarding solenoid valve is closed.
As described above, in each of these water purification apparatuses, water purifier, and water purification system, when the period of time during which the water is not passing is longer than the predetermined period of time, the notification is made so as to perform the water discarding of the given quantity, or the water discarding of the given quantity is automatically performed. This is because in each of these water purification apparatuses, water purifier, and water purification system, it is mainly considered that the remaining water is discarded.